The following generally relates to positioning systems, and more specifically relates to optical systems used to automatically locate Z-forms with precision for reinforcement of composite structures.
Manufacturers utilize composite materials in a wide variety of applications. The relatively high strength-to-weight ratio, stiffness-to-weight ratio, and fatigue characteristics of composites have made the material increasingly popular with aerospace, automotive, and other industries.
To join individual composite parts, manufacturers often use conventional fasteners; however, the use of conventional fasteners typically requires access to both sides of the assembly, and such access can be limited. In these cases, manufacturers usually employ alternative attachment means. For example, the composite parts can be adhesively joined or co-bonded, but these methods often result in an inadequate bond. For a more secure bond, manufacturers insert reinforcing pins, commonly called “Z-pins,” through the parts normal to the bondline. As such, the Z-pins bear a portion of the loading that might otherwise damage the bondline.
Manufacturers typically insert Z-pins with largely non-automated processes. For example, multiple Z-pins held within a foam carrier (collectively referred to as a “Z-form”) are manually positioned on a target area of the composite part. Then, an insertion tool is manually located over the Z-form, after which the inserting tool utilizes ultrasonic energy to force the Z-pins out of the Z-form and into the target area of the composite. However, manufacturers desire a more automated process so that the Z-pinning process can be employed in high yield production faster and cheaper.
U.S. Pat. No. 5,832,594 to Avila and U.S. Pat. No. 5,919,413 to Avila both disclose a hydraulic Z-pin insertion tool and a method of using the same. As described in these patents, Z-forms are loaded into the tool, which is then positioned over an area of composite to be pinned, and an actuator within the tool drives the pins into the composite. Thus, the tool and insertion method disclosed in the Avila patents allow Z-pins to be inserted automatically, and production costs are partially reduced as result. However, portions of the Z-form can become jammed within the tool as the insertion process takes place. Once jammed, manual labor is required to clear the jam, thereby increasing manufacturing time. As a result, the cost savings resulting from the automated process are less significant or, in some cases, eliminated.
Thus, there remains a need among composite manufacturers for an improved automated Z-pinning process. Ideally, the automated process would involve pre-positioning the Z-form on the composite target area, separate from the insertion tool, because there is less chance for the insertion tool to become jammed. In order to achieve proper pinning in this manner, the insertion tool should be located according to the position of the Z-form with a high degree of precision (e.g., approximately +/−0.025 inches). However, manual positioning of the composites, tool, and Z-form typically results in a cumulative error of approximately +/−0.25 inches.
Therefore, it is understood that there is an ongoing need for an apparatus that enables a Z-pin insertion tool to be located with precision relative to a Z-form. Such a tool and its method of use would allow for a more efficient automated manufacturing process and advantageously reduce manufacturing time and costs.